1. Field of the Invention
The present invention relates to a pump, and more particularly to a DC brushless motor pump.
2. Description of the Related Art
Refer to FIGS. 1 and 2 shown as a 3D exploded view and a partially sectional view respectively illustrating a conventional motor pump. The conventional single-phase winding brushless motor pump 1 comprises a motor 10, a body 11, a fan blade member 14, and a front cover 15.
The body 11 includes a housing 112 that defines a chamber 111 and a cover 113 sealing the chamber 111. The housing 112 is provided with a flange 115 arranged at a front sidewall 114, and a cylinder 116 extended into the chamber 111 from the flange 115; thus an opening 117 is formed on the flange 115 of the front sidewall 114 and a pair of L-shaped connectors 118 formed symmetrically about the flange 115.
The motor 10 includes a single-phase winding coil unit 12 and a rotor 13. The rotor 13 includes a rotating shaft 131 and an annular magnetic member 132 surrounding an outer circumference of the rotating shaft 131. The fan blade member 14 is mounted on a front end of the rotating shaft 131, and the rotor 13 is inserted into the cylinder 116 through the opening 117 such that the fan blade member 14 is positioned outside the opening 117. The coil unit 12 is mounted in the chamber 111 surrounding the cylinder 116. Silicon steel laminations 121 of the coil 12 oppose the magnetic member 132 so that the coil 12 is subjected to the magnetic attraction force of the magnetic member 132 to be positioned outside the circumference of cylinder 116.
The front cover 15 includes a basal wall 151, a circumferential wall 152 extending from an outer circumference of the basal wall 151 to thereby define a hollow 150, and a pair of evenly spaced circular extension portions 154 horizontally outwards extending from the circumferential wall 152 and forming two gaps 153. The basal wall 151 is provided with a water intake tube 155 axially corresponding to the fan blade member 14. The circumferential wall 152 is formed with a water outlet tube 156. When the gaps are arranged up and down, the front cover 15 may be aligned to the connector 118 of the body 11 so that, after the front sidewall 114 is kept close to the body 11 and then rotates at an angle, the extension portion 154 may be wedged to the connector 118 and the front cover 15 may be mounted onto the body 11. The water intake tube 155 and the water outlet tube 156 are hollow tubes that respectively extend from outwards the basal wall 151 and the circumferential wall 152.
With reference to FIG. 3 as a circuit block diagram for a conventional motor, the conventional synchronous motor pump further includes an excitation circuit 16. When external power is supplied to the excitation circuit 16, the coil unit 12 is operated to generate a magnetic flux effect to thereby induce the rotor 13 to rotate. Through such operation of the motor 10, water enters through the water intake tube 155, as shown in FIG. 1, and then is centrifugally exhausted via the water exhaust tube 156 by the rotation of the fan blade member 14 fixed to the rotating rotor 13. Hence, pumping of a liquid substance such as water is realized.
Although the conventional pump can achieve its intended purpose, it nevertheless suffers from many drawbacks. Refer to FIG. 4 as a sequence diagram of continuous power supply at a consistent frequency. The conventional pump is supplied with AC power and thus operates with a continuously constant power at 50 Hz or 60 Hz, so the motor 10 is powered with full load from beginning to end. However, the motor 10 is driven with higher power than operation current; for example, the motor 10 operates with a voltage of 115V/60 Hz at a rotation speed of 3600 rpm, and when the voltage is dropped by a transformer to around 100V/60 Hz, the motor still runs constantly at 3600 rpm and the quantity of water is same; thus, around 15% voltage is not helpful and is changed into power loss. Accordingly, at the beginning of operation with full load, the efficiency cannot be enhanced in operation and even more power is much consumed.
Consequently, because of the technical defects of described above, the applicant keeps on carving unflaggingly through wholehearted experience and research to develop the present invention, which can effectively improve the defects described above.